Pseudomonic acid A, also known as mupirocin, represents a major component of pseudomonic acid. Pseudomonic acid A was first discovered by A. T. Fuller et al. in 1971 [Nature 234, 416 (1971)]. Pseudomonic acid A has the following chemical name and trade names: [2S-[2 alpha (E),3 beta, 4 beta, 5 alpha [2R*, 3R*(1R*, 2R*)]]]-9-[[3-Methyl-1-oxo-4-[tetrahydro-3,4-dihydroxy-5-[[3-(2-hydroxy-1-methylpropyl) oxiranyl]methyl]-2H-pyran-2-yl]-2-butenyl]oxy]nonanoic acid, pseudomonic acid A, trans-pseudomonic acid, BRL-4910A, Bactoderm, Bactroban, and Turixin. Pseudomonic acid has topical antibacterial therapeutic activity.

Pseudomonic acid A is a potent antibiotic against both Gram(+) bacteria (Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae, Klebsiella pneumoniae) and some Gram(−) bacteria (Haemophilus influenzae, Neisseria gonorrhoeae) [A. Ward, D. M. Campoli-Richards: Drugs 32, 425-444 (1986)]. The mode of action is believed to involve the inhibition of isoleucine-tRNA synthase enzyme that affects the peptide synthesis in bacteria [J. Hughes and G. Mellows: Biochem. Journal 191, 209-219 (1980)]. The disclosure of these references is incorporated by reference in its entirety.
Presently, pseudomonic acid is produced by cultivation of Pseudomonas sp. Conventional Fed Batch Technology involves feeding nutrients at the beginning of the fermentation process without regulating pH and nutrient concentration. Because of the fluctuation of pH levels and nutrient depletion during a Fed Batch fermentation process, the yield of pseudomonic acid is often diminished. A concomitant increase in impurity often represents a major drawback for Fed Batch Technology.
There is a constant need to improve fermentation processes for preparing pseudomonic acid, particularly increasing the degree of purity of pseudomonic acid A product (e.g., substantially reducing the pseudomonic acid B impurity).